As color filters formed on the elements for the purpose of display of color images in a solid-state image sensing device and a liquid crystal display, a color filter comprising a yellow filter layer, a magenta filter layer and a cyan filter layer disposed on the same flat surface of a substrate and adjacent to each other, and a color filter comprising a red filter layer, a green filter layer and a blue filter layer, disposed on the same flat surface of a substrate and adjacent to each other, are known. In these filter layers, zone patterns or mosaic patterns are formed.
As methods of manufacturing the above-mentioned color filters, various methods have been proposed thus far. Among these, a so-called color resist method is widely put into practice, the method involving repeating required times a step of carrying out patterning by light-exposure and development of a photosensitive resin composition containing a pigment.
A color resist method is a method of preparing a color filter by photolithography by using a colored radiation-sensitive composition in which a pigment is dispersed in a photosensitive composition. This method uses a pigment and thus is stable against light, heat, or the like and also is sufficient in positioning precision on account of carrying out patterning by photolithography, and so is a suitable method of preparing a color filter for a large screen, high definition color display.
When a color filter is prepared by means of a pigment dispersing method of dispersing a pigment as described above, the method involves repeating an operation including applying a radiation-sensitive composition onto a glass substrate with a spin coater, a roll coater or the like to form a coated film, and then obtaining colored pixels by pattern exposing and developing the coated film in accordance with a desired number of hues while changing the colorant, to obtain a color filter. As the composition used in the pigment dispersing method, negative type photosensitive compositions containing an alkali-soluble resin, a photopolymerizable monomer and a photopolymerization initiator are known (e.g., see Patent Documents 1 to 8, 12 and 13).
Recently, still higher definition is desired for color filters for solid-state image sensing devices. Conventional pigment dispersing compositions as described above, however, have problems in that resolution is not improved, unevenness of color is generated due to coarse particles of a pigment, and the like. Hence, the compositions are unsuitable for applications, such as solid-state image sensing devices, in which micro-patterns are required.
For such problems, the use of dyes has been conventionally proposed (e.g., see Patent Documents 9 and 10). Additionally, the use of positive type photosensitive compositions has also been proposed (e.g., see Patent Documents 11 and 12). However, a curable composition containing a dye has the following problems below and needs further improvements:
(1) Dyes are generally inferior in heat resistance, light resistance, and the like compared to pigments, and thus are not sufficient in fastness,
(2) When the molar light absorption coefficient of a dye is low, a large amount of the dye must be used, so that the amounts of other components such as a polymerizable compound, a binder, a photopolymerization initiator have to be relatively decreased, leading to decrease in curing property at the time of curing the composition, heat resistance of a cured portion, and developability of a non-cured portion, and the like,
(3) Dyes frequently interact with other components in the curable composition, so that the adjustment of developability (solubility) of a cured portion and a non-cure portion is difficult.
Accordingly, the fastness of dyes that have been conventionally used in a photosensitive composition is not sufficient. Moreover, the solubility of dyes in photosensitive compositions are low, and thus the dyes sometimes precipitate in a liquid or in a coated film. In addition, it is difficult for a composition to contain dye in a high concentration.
On the other hand, it is known that a yellow dye and a cyan dye are used in a green-colored filter array of a color filter (e.g., see Patent Document 10). However, the heat resistance and light resistance of the copper phthalocyanine colorant used are insufficient, and further improvements thereof are desired. Furthermore, although a phthalocyanine colorant containing a specific amine-based substituent is also known (e.g., see Patent Document 14), the heat resistance and light resistance of this colorant are also insufficient, and further improvements thereof are desired.
In addition, a phthalocyanine colorant having a substituent at an α-position has poor solubility in a resin liquid (solution containing a colorant, a resin, a monomer, an initiator, a solvent, etc.), so the improvement in the storage stability and the like of a resin liquid is desired (e.g., see Patent Document 15). Moreover, a color filter is disclosed that contains a phthalocyanine colorant substituted by a substituent having a nitrogen atom at an α-position; however, the colorant has poor solubility in an alkaline developer, so the improvement in the developability is desired (e.g., see Patent Document 16).
Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No. 1-102469
Patent Document 2: JP-A No. 1-152499
Patent Document 3: JP-A No. 2-181704
Patent Document 4: JP-A No. 2-199403
Patent Document 5: JP-A No. 4-76062
Patent Document 6: JP-A No. 5-273411
Patent Document 7: JP-A No. 6-184482
Patent Document 8: JP-A No. 7-140654
Patent Document 9: JP-A No. 6-75375
Patent Document 10: JP-A No. 2002-14221
Patent Document 11: Japanese Patent Application Publication (JP-B) No. 7-111485
Patent Document 12: JP-A No. 2002-14223
Patent Document 13: JP-A No. 2002-14220
Patent Document 14: JP-A No. 7-286110
Patent Document 15: International Patent Publication No. WO88/06175
Patent Document 16: JP-A No. 5-295283